This study will examine the relationship between movement of a specific cell surface enzyme with variations in the mitotic cycle, the state of the cytoskeleton and membrane protein and lipid content. Possible mechanisms involved in mobilizing and polarizing the Na+K+ATPase within plasma membranes during early development will be sought. Na+K+ATPase moves during cleavage of the sea urchin embryo from a single spot on unfertilized and fertilized eggs to a position in each cleavage furrow and at resulting apposed cell surfaces. Cell polarity is essential for normal cell function and differentiation, and may reflect polarity of lipids, proteins and carbohydrates in the cell membrane and underlying cytoskeleton. The same mechanisms that induce enzyme polarity may be pivotal in forming normal or abnormal cell polarity. Interferance with known mechanisms of membrane protein movement by specific treatments will be screened for altered polarization of embryo Na+K+ATPase. Drugs will be used to perturb microfilament assembly or sliding, microtubule assembly, lipid fluidity alteration, ligand-receptor interaction, interactions of cytoskeleton elements that are altered by local ion content, insertion or removal of proteins at secretion or endocytosis, and cell-cell interaction. Enzyme cytochemical experiments will pinpoint the time of the polarization relocations, catalog the cyclic changes in the content of isolated membrane fractions containing the enzyme and determine which agents perturb this. An effect by several agents will suggest an interaction of surface and cytoskeleton. Plasma membrane domains appear in three density gradient fractions and each will be further fractionated, using Con-A sepharose affinity chromatography, into two subfractions (one with Con-A receptors, and one not). These can then be analyzed for Na+K+ATPase activity, for lipid content by NMR following extraction, and for protein content by SDS electrophoresis. Comparisons at different times during the enzyme localization, and following various treatments will reveal stability or cyclic or random changes in content. Stability of membrane content would suggest a passive membrane role in the relocation. Identification of factors which play an active role in patterned localization of Na+K+ATPase within plama membranes during early development will be attempted.